The Catalan giants, who are top of the La Liga table with 24 points to show from their opening nine games, will resume their 2024-25 campaign at home to Sevilla on Sunday evening.
Hansi Flick's side will then welcome Bayern Munich in the Champions League on October 23, before heading to Real Madrid for the first Clasico of the campaign three days later.
According to SPORT, Gavi, who has been out for almost a year with a serious knee injury, has now returned to full training alongside his teammates and is closing in on a return to action.
The report claims that Fermin and Olmo are also now available, with the pair recovering from muscular issues, and they could both be in the squad for the clash with Sevilla on Sunday night.
Gavi, Fermin, Olmo 'are all back for Barcelona'
Meanwhile, Lewandowski and Yamal are also allegedly fit after injury scares on international duty.
Lewandowski picked up a heavy knock while representing Poland during the international break, with the experienced striker seen limping after his country's clash with Croatia on Tuesday night.
However, the 36-year-old, who has scored 10 times in nine La Liga appearances this season, will reportedly be available for the clash with Sevilla on Sunday night.
Yamal has also allegedly handed Barcelona a major boost, with the 17-year-old said to have trained normally alongside his teammates on Thursday after recovering quickly from a hamstring issue.
Lewandowski, Yamal 'are also available after injury scares'
Barcelona revealed earlier this week that the teenager had picked up "a left hamstring strain" while representing Spain in their 1-0 success over Denmark last weekend.
However, Spain had claimed that Yamal was only suffering with "an overload", and the forward is now said to be back in full training ahead of his side's return to league action.
No risks will be taken with Yamal ahead of the matches against Bayern and Real Madrid, though, so it would not be a surprise to see him named on the bench against Sevilla this weekend.
Barcelona are still missing some important players despite the injury boost, with Ferran Torres, Marc-Andre ter Stegen, Marc Bernal, Andreas Christensen and Ronald Araujo all unavailable for selection.